Fix various problems (artifact order, api empty slice, assignee check, fuzzy prompt, mirror proxy, adopt git) (#33569) (#33577)

Backport #33569 by @wxiaoguang

* Make artifact list output has stable order
* Fix #33506
* Fix #33521
* Fix #33288
* Fix #33196
* Fix #33561

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

services/convert/repository.go

@@ -15,6 +15,7 @@ import (
 	unit_model "code.gitea.io/gitea/models/unit"
 	"code.gitea.io/gitea/modules/log"
 	api "code.gitea.io/gitea/modules/structs"
+	"code.gitea.io/gitea/modules/util"
 )
 
 // ToRepo converts a Repository to api.Repository
@@ -241,7 +242,7 @@ func innerToRepo(ctx context.Context, repo *repo_model.Repository, permissionInR
 		MirrorInterval:                mirrorInterval,
 		MirrorUpdated:                 mirrorUpdated,
 		RepoTransfer:                  transfer,
-		Topics:                        repo.Topics,
+		Topics:                        util.SliceNilAsEmpty(repo.Topics),
 		ObjectFormatName:              repo.ObjectFormatName,
 		Licenses:                      repoLicenses.StringList(),
 	}